Bad Sectors? Low-Level Format

It seems like there IS a way to “clear” bad sectors from your hard drive so you can use tools like GParted and the like – but I use “clear” in a very loose sense here!

First off, I MUST point out that I’m talking about file-system bad sectors. I’m NOT talking about physically damaged disk platters.

It seems NTFS keeps a list of bad sectors, and as long as those sectors are there, most partition-resizing tools will refuse to touch the disk with a 10 foot pole. HOWEVER… those of you who are beyond a certain age might remember something called a “low-level format.” (I’ll wait a moment for you while the moment of nostalgia passes.)

I thought I’d never see a need for low-level formatting in today’s world of super-reliable, super-fast, super-S.M.A.R.T, super-big hard drives – but it seems there is still one use for it.

The hard drive manufacturer’s low-level formatting utility will detect “bad” sectors and put them in the drive’s internal list of “bad” sectors – this is in the drive’s own firmware mind you, not in any file system structure (because at this point, your file system has been wiped out!).

Once this is done, the drive’s own controller will silently avoid those bad sectors – from any software’s point of view, those sectors or clusters just don’t exist anymore. (Since software rarely – if ever – directly addresses the disk, this sort of behind-the-curtain hiding of sectors or clusters is easily done by the drive’s on-board controller.)

After the low-level format, you can partition & format the drive normally, and your OS or whatever disk-checking tool you use should find a nice, clean disk with no errors.

Astute readers will note the downside to this “solution” – you have to low-level format your hard drive! Obviously this erases everything on it, without any possibility for recovery. So it’s not for the faint-of-heart.

And, coincidentally, it’s not for me, either. I’ve simply got too much data on my 2nd hard drive to back it up easily (and cheaply). And doing this to my primary hard drive (and thus being forced to re-install Windows) is simply out of the question.

For those that are interested, I found a lot of this information in this EASEUS Software Forum posting, while looking for the reason why (you guessed it) their software wouldn’t re-size my partition.

In the end, it looks like I’m stuck running the Windows 7 beta in a virtual machine – which is of course super-slow.

Maybe someday I can shell out the cash for an external hard drive so I can back up my data and do the low-level format… but until then… I’m stuck with my partitions the way they are. Bummer!!

Interested readers may want to catch up on the previous entries in this saga:

Author: Keith Survell

A geek, programmer, amateur photographer, anime fan and crazy rabbit person.

4 thoughts on “Bad Sectors? Low-Level Format”

  1. I had a very similar problem where my HDD was dying, so I bought a brand new 160GB drive. I partition cloned from old to new. The cloning process actually copied the bad sectors to the brand new drive.

    So I had a brand new drive, with bad sectors. I couldn’t use GParted, for the same reason as you, but I did find a way to solve the problem using the DFSee tool. There is a command NOBADS and you can use it to erase the bad-sector list contained in the ntfs partition info. Boot into DFSee FreeDOS tool, select the object to work with-> Partition-> NTFS volume. From the command just run the NOBADS command, and voila, all fixed, no messy syntax.

    After clearing the bad sectors, running another chkdsk /f /r, rebooting twice, finally Gparted was able to work properly. I knew there were no real bad sectors, they were carried over through my cloning process.

    This took me about 8 hours total time to figure out, research and experiment, but I’m happy to say, all is well and I hope this information may help someone.

  2. Beginning with the Vista version of CHKDSK, there is a /b switch that will reset bad sector information on an NTFS volume.

    I don’t know if other drive manufacturers offer this, but Hitachi users can repair bad sectors without a low-level format using their Drive Fitness Utility. It may be worth checking out your drive’s diagnostic software for something similar.

  3. This was incredibly helpful. I have the same problem as JW, so on Brian’s advice, I hooked up the drive to a computer with Vista and ran it with /b. Great solution.

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